1. Field of the Invention
This invention relates to a surgical handpiece for use during endoscopic surgical procedures for driving an elongated rotatable surgical instrument and aspirating material from the surgical work site. More particularly, this invention relates to a method for manufacturing the handpiece and a means for enabling the orientation of the instrument attached to the handpiece to be angularly adjusted relative to the axis of the handpiece. The invention also relates to a surgical handpiece having a novel, longitudinally activated aspiration control valve.
2. Description of the Prior Art
Surgical handpieces have long been used to house the mechanical and electrical components necessary to operate a variety of powered surgical instruments attached to the handpiece. While some such instruments are used in open surgical procedures, the use of surgical cutting instruments has also become well accepted in performing closed surgery such as arthroscopic or more generally endoscopic surgery. The terms "arthroscopic" and "endoscopic" may be used interchangeably herein and are intended to encompass arthroscopic, endoscopic, laparoscopic, hysteroscopic or any other similar surgical procedures performed with elongated instruments inserted through small openings in the body. In such surgery, access to the surgical site is gained by one or more portals and instruments used in the surgical procedure must be elongated to permit the distal ends of the instruments to reach the surgical site. Surgical cutting instruments for use in closed surgery are commonly referred to as "shavers" or "blades" and comprise an assembly composed of a rotatable inner member situated within a non-rotatable outer member. Such shavers conventionally have an elongated outer tubular member terminating at a distal end having an opening in the side and/or end wall to form a cutting port or window. An elongated inner tubular member is concentrically disposed in the outer tubular member and has a distal end disposed adjacent the opening in the distal end of the outer tubular member. The distal end of the inner tubular member has a surface or edge for engaging tissue via the opening in the distal end of the outer tubular member and in many cases cooperates with the opening to shear or cut tissue. The inner and outer tubular members both have hubs at their proximal ends to enable the shaver blade assembly to be attached to a handpiece to facilitate manipulation of the shaver blade as well as to provide power to the inner tubular member so it can be rotatably driven at its proximal end. The drive mechanism is normally a small electric motor situated in the handpiece and controlled by a foot switch, a finger actuated switch on the handpiece or switches on a console supplying power to the handpiece. The distal end of the inner tubular member can have various configurations depending upon the surgical procedure to be performed and the opening of the distal end of the outer tubular member has a configuration to cooperate with the particular configuration of the distal end of the inner tubular member. Cut tissue and irrigating fluid are aspirated through the hollow lumen of the inner tubular member to be collected via a tube communicating with the handpiece.
In such instruments, the cutting window at the distal end of the outer member is often fixed at a given angular orientation relative to the handpiece. The hub at the proximal end of the outer member is keyed to fit in a receiving collet having a keyway facing in only a particular orientation which necessarily causes the cutting window to face in a predetermined direction. The choice of where to position the keyway relative to other features on the handpiece is made during manufacture. However, in certain surgical procedures the surgeon may prefer to have the cutting window face in different directions relative to the handpiece, particularly if the handpiece has control switches or is shaped in a way which interferes with its use in certain window orientations.
While some mechanisms are known by which the angular orientation of the cutting window is adjustable, such mechanisms are often cumbersome and are difficult to operate during the course of an endoscopic surgical procedure. One known cutting window orientation adjustment method involves simply providing multiple keyways (or bayonet locking mechanisms), removing the shaver blade and reinserting the hub into the collet in a different position. Another known method utilizes a single keyway to fix the window relative to the collet and means to enable the collet itself to be unlocked and turned without removing the blade. This method, utilized for example on a APS High Speed Arthrotome manufactured by Hall Surgical, Carpinteria, Calif., requires a procedure in which the handpiece body and collet are each held, moving the collet distally a certain distance relative to the body, turning the collet to orient the window as desired and then releasing the collet to lock it in place relative to the body. While not necessarily detrimental in an open surgical procedure, this type of adjustment may in some instances be awkward to perform during the course of an arthroscopic procedure. An easier window orienting mechanism would be desirable.
While the ability to select the cutting window orientation is desirable, doing so with existing shaver blades destroys the blade recognition feature utilized in many arthroscopic shaver systems. This feature relies on encoding the blades with discrete magnets embedded in the hub of the outer tubular member and reading the position of these magnets with sensors in the handpiece. This information is used to control the speed of the drive motor and to perform other identification functions understood by those skilled in the art. Rotating the outer tubular member in order to orient the cutting window moves the magnets in the hub away from the sensors, thus providing inaccurate information to the control system operating the handpiece. It would be desirable to have the ability to orient the cutting window of a shaver blade without compromising the ability of the control system to read the code associated with the blade in use.
The ability to control the orientation of the cutting window should be considered in conjunction with the necessity for the surgeon to control the degree to which irrigating fluid and tissue debris is aspirated from the surgical work site. This is generally accomplished by providing the surgeon with a handpiece having an easily accessible aspiration control valve. Thus, the surgeon could hold the handpiece comfortably with the aspiration control button in a selected orientation while being able to orient the cutting window as desired. While aspiration controls for shaver blade handpieces are known, they are often either expensive to manufacture or difficult to use because the design of these controls is greatly dependent upon the manufacturing process utilized for the body of the handpiece. For example, one known finger activated suction control valve utilizes a single, longitudinally extending lever pivoted at the surface of an elongated handpiece about an axis perpendicular to the longitudinal axis of the handpiece. The lever is rotatable in a plane parallel to the axis. Another example utilizes a similar lever near the distal end of the handpiece but pivoted about an axis parallel to the longitudinal axis of the handpiece. This lever is rotatable in a plane perpendicular to the axis. In each of these examples the user must employ a side-to-side, lateral type of finger motion to manipulate the suction control valve.
Many surgeons prefer a suction control valve having an ergonomically more normal motion such as a forward/backward, longitudinal type of finger motion particularly if the handpiece is small and held like a pencil. One known forward/backward valve is in the form of a lever extending outwardly from the axis of the handpiece, the radially inner end of the lever attached to a rotatable apertured plug situated in a transverse channel drilled through the distal end of an axially aligned aspiration channel in a handpiece. The plug has a bore which, by rotation of the plug about its axis, is aligned in either an open or closed position by the forward/backward motion of the lever. Known handpieces having such a transverse control valve are expensive and difficult to manufacture.
Prior art surgical shaver handpieces are generally machined from bar stock in view of the desire to minimize the number of throughbores and openings which must be sealed. This necessitates the use of the aforementioned transverse aspiration control valves. Even in those instances where handpieces have a main throughbore for the motor, blade, etc. and another parallel throughbore for the aspiration channel, the aspiration control valves are only laterally adjustable.
It is consequently an object of this invention to produce a surgical shaver handpiece having a simplified longitudinally actuable aspiration control valve which is less costly and difficult to manufacture than known units.
It is another object of this invention to produce a surgical shaver handpiece in which aspiration control may be achieved by a longitudinally movable slide switch.
It is yet another object of this invention to produce a surgical shaver handpiece having a simplified longitudinally actuable aspiration control valve with a combination seal/bearing unit to support and seal the valve.
It is also an object of this invention to produce a surgical shaver handpiece in which the orientation of the cutting window of the outer member is easily adjustable without disengaging the blade from the handpiece.
It is yet another object of this invention to produce a surgical shaver handpiece in which the orientation of the cutting window may be changed while retaining the ability of the control system to read the code associated with the blade in use in any window orientation.